In recent years there has been a dramatic increase in the demand for online gambling & online casino sites using crypto currency. The reasons have to do with what makes crypto currency appealing in the first place, namely that it can be quickly transferred from person to person, and that it can be moved to and fro without the use of banks.
The demand for online gambling is ever increasing as is the demand for safe transfer of payment. Bitcoin appeals to online gamblers for just this reason. Money can be moved easily across international barriers too. In addition, crypto currency provides a way around restrictions on gambling using other currencies.